The present application is based on Japanese Patent Application No. 2001-64389, the entire contents of which are incorporated herein by reference.
The present invention relates to an ink jet recording apparatus having an ink jet recording head, mounted on a carriage to be reciprocatively moved, for ejecting ink droplets in accordance with print data. More particularly, the invention relates to an ink jet recording apparatus in which an operation mode of the wiping operation is changed in accordance with an amount of adjustment of a platen gap, which is carried out by a platen gap adjusting device, and a method of controlling the operation of wiping a recording head in the ink jet recording apparatus.
An ink jet recording apparatus based on the serial printing system includes an ink jet recording head, which is mounted on a carriage and moved in a main scan direction, and a paper feeding device for feeding a recording sheet in a sub-scan direction perpendicular to the main scan direction. The recording head ejects ink droplets onto a recording sheet in accordance with print data, and prints images on the recording sheet.
The ink jet recording head prints images on a recording sheet in a manner that ink is pressurized in the pressure generating chamber, and is ejected in the form of ink droplets from the nozzle orifices toward the recording sheet. Therefore, the nozzle orifices are frequently clogged, and this results in improper printing. Various causes of the nozzle clogging exist, and examples of them are increase of ink viscosity due to solvent evaporation through the nozzle orifices, ink solidification, and dust attaching to the orifices.
To avoid the clogging trouble, this type of the ink jet recording apparatus uses a capping device for hermetically closing the nozzle forming surface of the recording head in a non-print mode. The capping device serves as a lid for preventing the ink at the nozzle orifices of the recording head from being dried. Further, it functions to recover the ink droplets ejection capability of the recording head. That is, when the nozzle orifices are clogged, the nozzle forming surface is sealed with the capping device, a negative pressure is applied from a suction pump to the clogged nozzle orifices to forcibly suck the ink therefrom. In this way, the clogging of the nozzle orifices is removed.
A process of forcibly sucking the ink from the clogged nozzle orifices, which is executed for removing the clogging of the recording head, is called a cleaning operation. It is executed when the printing is started again after the ink jet recording apparatus is not used for a long term or when the user recognizes printing failure and operates a cleaning switch, for example. In the cleaning operation, under a negative pressure by the suction pump, the ink is sucked and discharged into the capping device from the recording head, and then the nozzle forming surface is wiped with a strip-like wiping member formed of a rubber material, for example.
By executing the wiping operation, the ink that is attached to the nozzle forming surface of the recording head by the cleaning operation is wiped out from the nozzle forming surface, thereby solving the problem that ink falls in droplets from the recording head. By executing the wiping operation, meniscuses formed at the nozzle orifices are reshaped, whereby the ejection of ink droplets from the recording head is stabilized, and highly precise printing is guaranteed.
This type of ink jet recording apparatus is provided with a platen gap adjusting device which adjusts a gap between a recording head and platen for guiding the recording sheet in accordance with a thickness of the recording sheet used for printing. Most of the platen gap adjusting devices are each designed such that when the device is operated, the recording head is moved with respective to the platen fixed.
In particular, in recent years, with diversification of printing, there is an increase of the market demand of using a relatively thick recording sheet for the printing sheet. With such a market demand, the necessity for the considerably increasing of an adjustable range of the gap adjustment by the platen gap adjusting device, when comparing with the conventional one, is present. In this circumstance, a movable range of the recording head when the platen gap adjusting device is operated is more and more increasing.
The wiping member is held with a wiper holder such that it is movable, for example, horizontally and to and from a movement path of the recording head. To the wiping operation, the wiping member advances to the movement path of the recording head, the tip of it comes in sliding contact with the nozzle forming surface of the recording head and is elastically deformed, and it wipes the nozzle forming surface of the recording head. Accordingly, a sliding contact pressure of the wiping member against the nozzle forming surface of the recording head is varied in accordance with a degree of the adjustment by the platen gap adjusting device.
For example, when the platen gap is set to be large, the nozzle forming surface of the recording head is moved away from the wiping member. An amount of interference against the nozzle forming surface by the wiping member decreases, and a sliding contact pressure against the nozzle forming surface by the wiping member also decreases. For this reason, where the platen gap is set at a large value, an efficiency of wiping the nozzle forming surface by the wiping member decreases.
At an instant that the ink is wiped out from the nozzle forming surface of the recording head and the sliding contact of the wiping member with the nozzle forming surface is removed, the wiping member is elastically returned to its original position. During the elastically returning operation of the wiping member, the wiped ink is scattered within the recording apparatus. To reduce a degree of the ink scattering, there is proposed a recording apparatus employing a control unit which decreases a moving speed of the carriage (recording head) near the end of the wiping operation by the wiping member, whereby the ink scattering degree is reduced.
A degree of deformation (bending) of the wiping member, which is in a sliding contact with the nozzle forming surface, depends on a degree of the adjustment of the platen gap. Accordingly, the end of the wiping operation of the wiping member is substantially varied, and hence a position at which the wiping member starts the elastically returning operation, is also varied. For this reason, there is a desire to vary a position to start the low speed driving of the carriage in accordance with the size of the platen gap.
The present invention has been made to solve the technical problems as mentioned above, and an object of the invention is to provide an ink jet recording apparatus which stably wipes the nozzle forming surface with the wiping member independently of the adjustment of the platen cap, whereby the ink scattering caused by he wiping member is effectively reduced, and a method of controlling the operation of wiping a recording head in the ink jet recording apparatus.
According to one aspect of the present invention, there is provided a first ink jet recording apparatus comprising: an ink jet recording head having a nozzle forming surface mounted on a carriage to be reciprocatively moved for ejecting ink droplets in accordance with print data; a wiping member which comes in sliding contact with the nozzle forming surface with the movement of said recording head, thereby cleaning the nozzle forming surface; and a control unit for controlling a wiping speed of the wiping member relative to said nozzle forming surface, which is performed with the movement of said recording head; wherein the wiping speed is controlled in accordance with adjusting information of a platen gap adjusting device.
In the first ink jet recording apparatus, when the adjusting information of the platen gap adjusting device indicates that a platen gap is large, a speed of wiping the nozzle forming surface by the wiping member is preferably controlled so as to be lower than the wiping speed when the adjusting information of the platen gap adjusting device indicates that the platen gap is small.
In another ink jet recording apparatus, a control unit is provided which controls the number of operations of wiping the nozzle forming surface by the wiping member, which is performed with the movement of the recording head, in accordance with adjusting information of the platen gap adjusting device.
In the second ink jet recording apparatus, when the adjusting information of the platen gap adjusting device indicates that a platen gap is large, the number of operations of wiping the nozzle forming surface by the wiping member is controlled so as to be larger than the number of wiping operations when the adjusting information of the platen gap adjusting device indicates that the platen gap is small.
In a third ink jet recording apparatus constructed according to the invention, a control unit is provided which decreases a speed of wiping the nozzle forming surface by the wiping member, which is performed with the movement of the recording head, at a time point near the end of the wiping operation by the wiping member, and for varying a deceleration start position of the recording head in accordance with adjusting information of the platen gap adjusting device.
In the third ink jet recording apparatus, when the adjusting information of the platen gap adjusting device indicates that a platen gap is large, a deceleration start position of the recording head is controlled so as to be located on a side from which the recording head approaches to the wiping member as compared to a deceleration start position when the adjusting information of the platen gap adjusting device indicates that the platen gap is small. Also in this ink jet recording apparatus, a deceleration start position of the recording head is preferably controlled so as to be a range from a position out of a nozzle forming area of the recording head to the end of the nozzle forming surface is set to be a range of the wiping by the tip of the wiping member.
Additionally, the control of changing the deceleration start position is performed in a manner that a drive speed of a carriage motor is decreased in accordance with information output from an encoder for detecting a moving position of the recording head.
According to another aspect of the invention, there is provided a method of controlling the operation of wiping an ink jet recording head in an ink jet recording apparatus having an ink jet recording head, mounted on a carriage to be reciprocatively moved, for ejecting ink droplets in accordance with print data, and a wiping member which comes in sliding contact with a nozzle forming surface with the movement of the recording head, thereby cleaning the nozzle forming surface, the method comprising the steps of: acquiring adjusting information of a platen gap adjusting device; setting a speed of wiping the nozzle forming surface by the wiping member in accordance with platen gap adjusting information acquired in the gap adjusting information acquiring step; and wiping the nozzle forming surface by the wiping member by moving the recording head in accordance with a wiping speed set in the wiping speed setting step.
In another recording head wiping control method, the following steps are executed: a step of acquiring adjusting information of a platen gap adjusting device; a step of setting the number of reciprocating operations of the recording head in accordance with platen gap adjusting information acquired in the gap adjusting information acquiring step; and a step of wiping the nozzle forming surface by the wiping member by moving the recording head in accordance with the number of reciprocating operations as set in the number of reciprocating operations setting step.
In yet another recording head wiping control method, the following steps are executed: a step of acquiring adjusting information of a platen gap adjusting device; a step of setting a deceleration start position of the recording head in accordance with platen gap adjusting information acquired in the gap adjusting information acquiring step; and a step of decreasing a moving speed of the recording head in a state that the wiping member is in sliding contact with the nozzle forming surface, in accordance with a deceleration start position as set in the deceleration start position step.
In one recording apparatus using the wiping control method, gap adjustment information output from the platen gap adjusting device is utilized, and a speed of wiping the nozzle forming surface by the wiping member, which is performed with the movement of the recording head, is varied in accordance with the gap adjustment information. For example, when the platen gap is adjusted to be large, an amount of interference of the wiping member against the nozzle forming surface decreases, and hence a sliding contact pressure against the nozzle forming surface is decreased. Accordingly, an efficiency of wiping the nozzle forming surface by the wiping member decreases. However, the decrease of the wiping efficiency is compensated for by decreasing the wiping speed of the wiping member when it wipes the nozzle forming surface.
In another recording apparatus using the wiping control method, gap adjustment information output from the platen gap adjusting device is utilized, the number of operations of wiping the nozzle forming surface by the wiping member, which is performed with the movement of the recording head, is set in accordance with the gap adjustment information. For example, when the platen gap is adjusted to be large, an amount of interference of the wiping member against the nozzle forming surface decreases as in the case mentioned above, and hence a sliding contact pressure against the nozzle forming surface is decreased. However, the wiping effect by the wiping member may be increased by executing the wiping operations plural times.
In yet another recording apparatus using the wiping control method, gap adjustment information output from the platen gap adjusting device is utilized, the deceleration start position of the recording head is varied in accordance with the gap adjustment information. In this case, a deceleration start position of the recording head is controlled so as to be set at an early position in the moving direction of the recording head or at a position in the advancing direction in accordance with the size of the platen gap. With the control, the deceleration start position of the recording head may be set at a position just before the end of the wiping operation of the wiping member. The scattering of the ink from the wiping member is effectively reduced.
In other words, a decelerating movement range of the recording head may be reduced by controlling the deceleration start position of the recording head in accordance with the platen gap. When the wiping member passes the end of the wiping operation, the recording head may be quickly moved to the print area. Accordingly, this feature substantially increases the through-put of the recording apparatus.